This invention relates in general to apparatus for cutting sheet material and deals more particularly with improved high velocity fluid jet cutting apparatus for automated production cutting of limp sheet materials such as fabrics, plastic, paper, leather, rubber and the like. In an apparatus of the aforedescribed general type, a high pressure fluid jet focused by a nozzle functions as an omnidirectional cutting "blade" which forms a narrow kerf. Such apparatus is particularly suitable for cutting intricate shapes from multi-ply materials, however, the high pressure fluid jet stream, which travels at supersonic speed as it leaves the nozzle of the cutting tool, necessarily contains considerable energy as it exits from material which it has cut even though the stream energy has been dissipated significantly in the cutting process. This residual energy poses a potential source of damage to the apparatus, and particularly the working surface which supports the material being cut, and generally must be dissipated before the cutting fluid can be collected to be recirculated within the apparatus or drained from it.
In an apparatus of the aforedescribed general type the sheet material cut by the fluid jet is usually compressed, at least in the region where the jet is operating. More specifically, compressive forces are applied to the sheet material in a direction generally normal to the plane of the material and the support surface on which it rests. A typical apparatus of the aforedescribed general type wherein air is evacuated from between the layers of material which comprise a lay-up to normalize or compress the lay-up into a hardened mass is illustrated and described in U.S. Pat. No. 3,877,334, issued to the Assignee of the present invention. This patent discloses apparatus which has a common vacuum-fluid collection chamber. While such apparatus is generally satisfactory, it has been found that air entrained in the fluid jet stream and entering the collection chamber tends to reduce the efficiency of the vacuum system and the normalizing or compressing efficiency of the apparatus.
It is a general aim of the present invention to provide an improved fluid jet cutting apparatus which includes improved means for supporting material to be cut to provide for retardation and dissipation of cutting jet energy after the jet exits from the material which has been cut. It is a further aim of the present invention to provide an improved fluid jet cutting apparatus which includes vacuum means for compacting or compressing a multi-ply lay-up of sheet material so that the lay-up reacts substantially as a solid, rigid body in response to the cutting action of the fluid jet.